Super Noisy Phono Pre--Help?

Unplug your cartridge leads and report back how much noise was present.

Could be an errant IC cable. Try swapping cables. Sounds like it could possibly be a ground problem to me.

Then the preamp started producing a random popping sound and a motor sound like there was poor electric motor plugged into the same outlet. I thought it was a tube, but swapping out tubes didn't change it. I took it to my local service department. They cleaned and resoldered some of the connections. Now the popping sound is gone, but the constant motor sound persists. The motor sound goes away if I disconnect my turntable.

I would not assume that the phono stage necessarily has anything to do with the problem. You didn't mention what turntable you have, but a possibility that occurs to me is that a capacitor associated with the AC wiring within the turntable has become leaky or otherwise defective. And it could be that the cleaning and resoldering that was done on the phono stage had nothing to do with the elimination of the popping sounds. Perhaps they just went away, probably temporarily if my theory is correct, as a result of the turntable being unpowered for some period of time, allowing the capacitor to temporarily recover to some degree.

Just a guess, but a possibility to consider. Good luck. Regards,
-- Al

Lostbears, when it was on the market I believe it's mentioned power supply enhancements for even quieter performance along with replacing the blue LED's under the tubes to a shade that blends with the glow of the tubes.
Never was a fan of the blue LED, reminds me of cheesy made in China gear. I've been tempted to unplug the blue front display.

Al, I had/have an issue with my Aesthetix Janus full function preamplifier that may be very like the one described by the OP. When the tt is "on", I heard a sound on the speakers that was very like that of a motor, the turntable motor. The sound was only present when the tt motor was running and immediately ceased when I shut it off, and only when the Janus was set to "phono". Extensive investigation suggested that the tt and the Janus were very well isolated acoustically from one another, so I tend to rule out the idea that a microphonic tube was picking up actual motor vibrations. Further, the tubes were not demonstrably microphonic in the first place. Switching outlets and grounding vs ungrounding the tt also had no positive effect. Finally, I faced the possibility that the coupling capacitors in the Janus, which I had force-fit onto the PCBs using longish leads, might be picking up motor noise "through the air". I then replaced those caps with smaller ones that allowed the use of much shorter leads, and this cured the problem. But it was very odd; I would not have thought that EM radiations from the motor could manifest as "the sound of a motor". I wonder whether something similar is going on here.